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We derive constraints on cosmological parameters using the power spectrum of galaxy clustering measured from the final two-degree field galaxy redshift survey (2dFGRS) and a compilation of measurements of the temperature power spectrum and…

Measurements of the $H_0$ and $\sigma_8$ parameters within the standard cosmological model recently highlighted significant statistical tensions between the cosmic microwave background and low-redshift probes, such as local distance ladder,…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-26 Rocco D'Agostino , Rafael C. Nunes

In this paper we employ a recent proposal of C. Tsallis and formulate the first law of thermodynamics for gravitating systems in terms of the extensive but non-additive entropy. We pay a particular attention to an integrating factor for the…

High Energy Physics - Theory · Physics 2022-12-28 Petr Jizba , Gaetano Lambiase

We perform a comprehensive cosmographic analysis of Friedmann cosmologies modified by non-extensive entropy frameworks, focusing on Tsallis, R\'enyi, and Kaniadakis entropies within a novel modified energy-momentum tensor approach. In our…

General Relativity and Quantum Cosmology · Physics 2025-09-30 A. Khodam-Mohammadi , M. Monshizadeh

We present cosmological parameter constraints on flat cosmologies dominated by dark energy using various cosmological data including the recent Archeops angular power spectrum measurements. A likelihood analysis of the existing Cosmic…

Astrophysics · Physics 2009-11-07 M. Douspis , A. Riazuelo , Y. Zolnierowski , A. Blanchard

We construct modified cosmological scenarios through the application of the first law of thermodynamics in the universe horizon, but using the generalized, nonextensive Tsallis entropy instead of the usual Bekenstein-Hawking one. We result…

General Relativity and Quantum Cosmology · Physics 2018-12-07 Andreas Lymperis , Emmanuel N. Saridakis

We consider the interacting Tsallis Holographic Dark Energy (THDE), with the Granda-Oliveros (GO) scale as the infrared (IR) cutoff, as dynamical vacuum. We analytically solved for the Hubble parameter, in a spatially flat FLRW universe…

General Relativity and Quantum Cosmology · Physics 2023-01-02 M. Dheepika , Titus K. Mathew

Measurements of weak gravitational lensing at low redshifts ($z\lesssim 0.5-1$), quantified by the parameter $S_8$, favor weaker matter clustering than that expected from the standard $\Lambda$CDM cosmological model with parameters…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-12 Vivian Poulin , José Luis Bernal , Ely Kovetz , Marc Kamionkowski

The cosmological parameters that I discuss are the Hubble parameter $H_0 \equiv 100 h$ km s$^{-1}$ Mpc$^{-1}$, the age of the universe $t_0$, the average density $\Omega_0$, and the cosmological constant $\Lambda$. To focus the discussion,…

Astrophysics · Physics 2007-05-23 Joel R. Primack

In this paper, we combine the latest observational data, including the WMAP five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the Baryon Acoustic Oscillations (BAO) and Type Ia Supernoave (SN) "Union" compilation (307 sample)…

Astrophysics · Physics 2008-11-26 Jun-Qing Xia , Hong Li , Gong-Bo Zhao , Xinmin Zhang

Given the persistence of various tensions in the "Cosmic Concordance" -- such as the "Hubble Tension", and possible departures from LambdaCDM time evolution -- seen from combinations of complementary data sets (e.g., Cosmic Microwave…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-19 Brett Bochner , Aiden Jin

We investigate constraints on some key cosmological parameters by confronting metastable dark energy models with different combinations of the most recent cosmological observations. Along with the standard $\Lambda$CDM model, two…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-14 Xiaolei Li , Arman Shafieloo , Varun Sahni , Alexei A. Starobinsky

In the realm of the $\omega$CDM cosmological model with quiescence or quintessence as the dark energy, characterized by $\omega>-1$, there exists a fixed value of $H(z)$ at $z=-1$, devoid of dependency on other cosmological parameters. To…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-16 Cheqiu Lyu , Wei Hong , Tong-Jie Zhang

The $\Lambda$CDM model provides a good fit to a large span of cosmological data but harbors areas of phenomenology. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-14 Eleonora Di Valentino , Olga Mena , Supriya Pan , Luca Visinelli , Weiqiang Yang , Alessandro Melchiorri , David F. Mota , Adam G. Riess , Joseph Silk

Chandra observations of large samples of galaxy clusters detected in X-rays by ROSAT provide a new, robust determination of the cluster mass functions at low and high redshifts. Statistical and systematic errors are now sufficiently small,…

We study the reconstructed deceleration parameter splitting the data in different redshift bins, fitting both a cosmographic luminosity distance and also assuming a flat $\Lambda$CDM model, using the Pantheon+ sample of type Ia supernova…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-20 Erick Pastén , Victor Cárdenas

In this work, we study two scenarios of the Universe filled by a perfect fluid following the traditional dark energy and a viscous fluid as dark matter. In this sense, we explore the simplest case for the viscosity in the Eckart formalism,…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-22 L. Herrera-Zamorano , A. Hernández-Almada , Miguel A. García-Aspeitia

The paper investigates the Tsallis holographic dark energy (THDE) model in accordance with the apparent horizon as an infrared cut-off, in a non-flat universe. The cosmological evolution of the deceleration parameter and equation of state…

General Physics · Physics 2020-01-16 Vipin Chandra Dubey , Umesh Kumar Sharma , A. Beesham

We present cosmological parameter constraints from a tomographic weak gravitational lensing analysis of ~450deg$^2$ of imaging data from the Kilo Degree Survey (KiDS). For a flat $\Lambda$CDM cosmology with a prior on $H_0$ that encompasses…

One of the most prominent challenges to the standard Lambda cold dark matter ($\Lambda$CDM) cosmology is the tension between the structure growth parameter $S_8$ constrained by the cosmic microwave background (CMB) data and the smaller one…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-04 Lu Huang , Zhiqi Huang , Huan Zhou , Zhuoyang Li